A number of profiled tubes are known for use in tube heat exchangers, due to the broad application of heat exchangers. Tube heat exchangers which are comprised of a matrix of circular tubes are used in numerous fields such as, for example, in process technology or in heating plant structures. Circular tubes are characterized by low manufacturing costs and high resistance to internal pressure. However, if matrices with circular tubes are subjected to high flow velocity of the surrounding fluid, this leads to undesirably high pressure losses and tuburlence in the flowing fluid. This turbulence may cause vibrations in the tubes of the matrix, which adversely affect the fatigue strength of the matrix and its effectiveness. These conditions have led to more favorably shaped tube profiles, of lancet or oval shape, as disclosed in DE 33 27 660 A1, EP 0 360 899 B1 and DE 36 10 618 A1, Such tube profiles can be produced at low cost by bending processes and they are used in aircraft and spacecraft in cross-counterflow heat exchangers in which the tubes are bent in U-shape, for example, according to DE 36 10 618 A1. Such tubes can also be used in gas turbines and diesel engines of aircraft and vehicles, as well as in stationary plants. However, if lancet, ellipse-shaped or oval profiled tubes are subjected to high internal pressure, the limits to their use are rapidly revealed, since the high pressure leads to expansion deformation, and in the worst case to leakage.
A stacked arrangement of teardrop shaped profiled tubes in a heat exchanger matrix is disclosed in GB 468,980, whereby the flow-favorable shaped profiled tubes with their sharp edges can be aligned either in the direction of flow or opposite the direction of flow.